An apparatus for separating particles from each other using a difference in specific gravities has been widely used in a dry coal preparation field, a sorting field for recycling waste plastic, a field for purifying precious metals such as rare earth resources, and the like.
In particular, in the dry coal preparation field, a run of mine coal which is mined from a coal bed contains a large amount of coal and has a mixture of clean coal having a small amount of ash and a gangue which is a fragment of rock. When the clean coal includes the gangue, a quantity of heat may be reduced and harmful gas (SOx) may occur, during a combustion process and mica, chlorite in the gangue and alkaline components (K2O and Na2O) which are included in clay, and the like have a reduced melting point of ash during a combustion process, such that slagging or fouling may occur inside a boiler of a thermal power plant, which is a factor of shortening lifespan of the boiler.
Therefore, to improve the combustion efficiency and extend the lifespan of the boiler, attempts to develop a technology for removing the gangue mixed in the run of mine coal by a physical method have been conducted.
Korean Patent No. 1010940 which is the related art discloses an apparatus for improving low grade coal into high quality coal including: an abrasion crusher which includes a main body of a crusher which is provided with a receiving part to receive both of low grade coal of which the ash content is a predetermined level or more and water, a plurality of friction balls which is received in a receiving part of a main body of the crusher to crush the coal by collision and friction with the coal, and an agitator which is rotatably disposed in the main body of the crusher to agitate the coal and the friction ball so as to provide mutual collision and friction between the coal and the friction ball; a screen which is installed over the receiving part of the abrasion crusher and provided with a plurality of transmit holes through which only particles having a predetermined size or less may pass; and a collector supply apparatus which supplies a collector hydrophobicizing the crushed coal particles to the receiving part so as to make the coal particles crushed by the abrasion crusher float toward a top portion of the receiving part. In summary, the related art is concerned with the run of mine coal to be sorted into clean coal particles and gangue particles by flotation.
However, the related art requires a post-treatment process of performing dehydration and drying the processed coal and therefore a lot of costs may be required.
Therefore, there is a need to develop various dry separation apparatuses for solving the above problems.